1. Field of the Invention
The present invention relates to compounds which act both as muscarinic receptor antagonists and beta2 adrenergic receptor agonists. The present invention also relates to processes for preparing such a compound, compositions which contain such a compound, therapeutic uses of such a compound, and combinations of such a compound with other pharmaceutical active ingredients.
2. Discussion of the Background
Pulmonary disorders, such as asthma and chronic obstructive pulmonary disease (COPD), are commonly treated with bronchodilators. A known class of bronchodilators consists of beta-2 adrenergic receptor agonists, such as salbutamol, fenoterol, formoterol and salmeterol. These compounds are generally administered by inhalation.
Another known class of bronchodilators consists of muscarinic receptor antagonists (anticholinergic compounds), such as ipratropium and tiotropium. These compounds are also typically administered by inhalation.
Inhaled formulations of both beta-2 agonists and muscarinic receptor antagonists are valuable agents in the treatment of asthma and COPD, with both classes of agents providing symptomatic relief due to their ability to relax constricted airways. Observations that the bronchodilator effects of the two classes of agents were additive, prompted studies with combinations of the two agents. In 1975, it was shown that beneficial effects could be achieved by combining two ingredients such as fenoterol and ipratropium bromide in a single aerosol. This prompted the development of fixed dose combinations of ipratropium bromide firstly with fenoterol (Berodual, introduced in 1980), and then with salbutamol (Combivent, introduced in 1994).
More recently the availability of both long-acting muscarinic antagonists and long-acting beta-2 agonists prompted to the development of combinations of these agents. For example, WO 00/69468, which is incorporated herein by reference in its entirety, discloses medicament compositions containing a muscarinic receptor antagonist, such as tiotropium bromide, and beta-2 adrenergic receptor agonists, such as formoterol fumarate or salmeterol, and WO 2005/115467, which is incorporated herein by reference in its entirety, discloses a combination which comprises a beta-2 agonist and an antagonist of M3 muscarinic receptors which is a salt of 3(R)-(2-hydroxy-2,2-dithien-2-ylacetoxy)-1-(3-phenoxypropyl)-1-azoniabicyclo[2.2.2]octane.
An alternative approach to the development of fixed dose combinations is the identification of molecules that combine both activities of muscarinic antagonism and beta-2 agonism. In fact compounds possessing both beta-2 adrenergic receptor agonist and muscarinic receptor antagonist activity are highly desirable since such bifunctional compounds would provide bronchodilation through two independent mechanisms of action while having a single molecule pharmacokinetics.
Such kind of compounds was described in some patent applications, such as WO 2004/074246, WO 2004/074812, WO 2005/051946, WO 2006/023457, WO 2006/023460, WO 2010/123766, WO 2011/048409, and co-pending patent application WO 2012/168359, all of which are incorporated herein by reference in their entireties.